Pinnacle seems to have something that works, with the Dragon Skin armor. they also seem intent on making shit up to make it sound even better. seems like a pretty stupid way to go about things, to me.

though i honestly wouldn't be surprised to find that much of the confusion stems from disinformation spread by other armor manufacturers. defense contracting is big pie that is cut into fairly big pieces--losing one's piece to some snot-nosed newcomer would be disastrous for the loser.

looking over their site again, i see what they've done: they've created an in-house set of standards that happen to be named the same as NIJ, and includes the NIJ standards. as for the "classified" crap, well, i googled and found the "classified" information within two clicks.

A few years ago I had a freind who worked out the physics of the SAPI plate/vest combination used by the military. Not sure what method he used, but in theory a SAPI plate in a vest can stop... once.... a .50 BMG. Of course, this was with no concern for trauma to the structure (body) supporting the vest, only where the slug wound up.

I would love to see that tested before I'd bet my life on it.


The future is becoming more clear, however. Modern armor is outpacing small arms, and light armored vehicles are far more useful to modern military doctrines than heavy tanks.

But the clear winner is the RPG... and I'm not talking games. I can forsee future militaries all but dispensing with small arms all together and focusing on light anti-armor weaponry, particularly as body armor gets more universal.

to an extent. i think what you'll see most often is what the Hezbollah used against Israel: small teams consisting of a few guys with rifles and one guy with an RPG. the rifle guys keep the enemy's heads down (body armor is great and all, but it only protects what it covers--and i don't think we'll ever see body armor that offers 100% effective 100% coverage, which means that when someone shoots at you, you're still gonna want to duck), while the RPGer takes something out. then they all disappear into a spider-hole and are gone.

Actually, the SAPI plates I wore were close to an inch thick. Now, part of that was anti-spalling or something (squishy backsides, like foam rubber), but they were a lot thicker than 10mm of plate.

And like I said, I wouldn't bet on it without seeing it done first....

Sorry, to address the rest of your post:

The US military is seeing a much lower incident of 'wounding' hits currently. There are a far greater proportion of maiming (limb removal) and killing injuries currently sustained. Part of this is body armor, which HAS proven effective. I've seen a photo of an infantryman in Bagdad who was showing off his bruises. He'd been shot on three seperate occasions in one week of patrolling, two hit his armor and were stopped, one hit his arm and was minor enough to not remove him from combat duties.

The other factor is improved medical abilities to prevent 'bleed outs' along with superior first aid training provided to every soldier.

Lastly, of course, is the rise in the use of explosives as primary weapons. The insurgents/guerrillas/enemy combatants rely less and less upon conventional small arms simply because they are horribly ineffective, not just due to 'mounted patrols' but even against soldiers doing house to house patrols on foot. Small arms fatalities are exceptions rather than the rule, and that's using current body armor techniques. The future of body armor is much brighter than the future of small arms. You do the math.

I meant they are about equivalent to 8 to 10 millimeters of rolled homogenous armor steel in their ability to defeat small arms rounds when properly backed: they can deal with 7.62x51mm or 7.62x54mmR FMJs no trouble (~4-5mm RHA), often stop semi-armor piercing mild steel core rounds of these calibers (~7-8mm RHA), but would be expected to fail against the NIJ test round for level IV, .30-06 M2 AP (~10-11mm).

A significant portion of the thickness is indeed the backing material, which is often of similar materials (polyaramides) as the vest in which they are inserted. The rest is usually aluminum oxide, silicon carbide, or, as I've understood is the case at least with the standard ESAPI plates, boron carbide. I don't know enough about any such designs to say what thicknesses of any of those would correspond to what sort of protection.

I do feel that RPGs specifically will not become a primary anti-personnel weapon for serious militaries any time soon. They are simply too cumbersome and inaccurate and their ammunition is too massive for that. Thermobaric and other anti-personnel munitions help make them an effective fire support weapon, but not so much the biggest casualty causer. The RPG-7 is just too handy at the moment for the groups in question.

Body armor capable of stopping even magnum rifle dedicated AP rounds is still well in the realm of imagination. It's impossible to say when such might come out, what it will look like (weight, coverage, loss of mobility, durability), how expensive it will be, etc. It's also hard to say what sort of advances in weapon technologies we are going to see by then. Hence it's impossible to say with any authority in what way such armor would change the standard weaponry of infantry in armies potentially facing it. If I had to hazard I guess, I'd look at the high-velocity 40mm HIWS platform shown off by FN at Blackwater some years ago.

Of course I might be horribly wrong.

I would be somewhat disturbed to discover that the SAPI plate did not provide superior value to an equal thickness of rolled steel. Lighter than rolled steel helps a bit, undoubtedly but...

My understanding of armor technologies is that composite armors are much stronger per thickness and density than homogenous armor. I expected that the SAPI plates took that into account, and were not merely some form of ceramic by itself (metal plates inside, yadda yadda). Composites wind up being superior than the sum of their parts by a significant margin because they gain the 'best of both worlds' mentality and because as the projectile passes through each layer of the composite it winds up shedding more energy and penetration value than if it were spending all that energy on the first impact. But I feel I'm being unclear here.

Take the idea of 'face hardened steel' armor. The idea here is that harder materials are more brittle than softer materials, which give more. If only the impact surface is hard, then you gain overall armor, it takes greater impacts to even affect the steel, but as the substrata of metal is not tempered, and is thus malleable, rounds that hit hard enough to break through the hardening do not simply shatter the plate and pass through it, but must also deform the thicker, softer metal underneath, consuming far more energy than going through an equivilent thickness of either hard or soft metal.

The same is true, only moreso of composited layers. By alternating between hard and soft layers you multiply the protection value significantly. Each layer strips away energy from the projectile, deforms it potentially, ruining it's ability to apply maximum energy to a minimum of surface area.

Now, if SAPI (not sure where your E comes from, the ones I had were just SAPI...) plates are not significantly compositied all that is moot. The question remains this: Does the amount of energy transfered into the plate bleed off enough from a BMG round to prevent it from passing through the stacked layers of Kevlar underneath it? Further, does the plate deform standard rounds enough to reduce their ability to penetrate? It's a given that the plate itself is going to be reduced to uselessness in the attack.

Now I need to scrape togther a few hundred dollars for a SAPI plate to expirement with....

See, that's the disturbing part... composite armor is relatively easy to make in simple form. A softer metal core in the SAPI plate (Boron Carbide is hard and brittle), and we are talking of a minimal thickness here (1mm maybe? Not an armor engineer....) about midway through would have a tremendous added value.

In theory (energy bleed): When a round strikes the Boron Carbide it has to transfer kinetic energy into the Carbide, if it can transfer enough it breaks the carbide... which I believe shatters under impact rather than deforming. Depending on the round in question, there is probably significant deformation from impact, reducing its profile (like a dulled knife cuts less deep than a sharp one for the same force). Now, a single solid peice of Boron Carbide will absorb the shock all at once, to the best of its ability to transfer kinetic energy. But a composited layer will not absorb any energy until it is struck by the incoming round itself. A soft layer will absorb more energy because it needs to be pushed out of the way, rather than be overwhelmed, and because the incoming projectile is presumably already deformed from the initial impact it drags more against the soft layer. Then you have another hard layer which again requires a single massive blow to even affect, but once affected is useless, though again it takes energy from the projectile... repeat until you are out of layers.


Now: If we know a 7.62mm round is 'stopped' by the ESAPI and the .50 is not, let me ask you this...

Does the impact of the 7.62 significantly ruin the ESAPI, or by 'Stopped' do you mean it was unable to overcome the hardness of the Boron Carbide and 'bounced'...

Because the theory promulgated (ohhh... big word day... ) by my buddy was that the ESAPI would be destroyed by the .50... but in the process would bleed off so much kinetic energy that the round in question had no significant penetration after. I can imagine that a body armor manufacturer would not necessarily consider it 'stopped' if it destroyed the plate and landed on the other side of the test platform, even if the round had no real ability to do anything at that point.

You seem much more connected on the science end than I am, so I'd like your take on that. I just wore the damn things... And I wouldn't wear Chobham.. I hear it's got uranium in it....

I'm sure if far more effective body armor designs were both cheap and easy to make, they'd be in widespread use. Well, even if they weren't cheap they'd be used -- the best boron carbide plates cost upwards of $1000 each.

The NIJ level IV armor standard only requires a single .30-06 M2 AP round (capable of piercing 10-11mm of armor steel at 100 meters) to be stopped, the original assumption being that body armor that highly rated is often cracked by a single such impact. Some plates can handle multiple such impacts, but greater threats can still plow right through with a single hit. How well the SAPI and ESAPI plates can handle multiple impacts from 7.62x51mm and similar steel core AP rounds, I have no idea.

To qualify for NIJ level III any plate will have to be able to deal with six 7.62x51mm M80 ball impacts at 2750fps, with each impact being 3" or more from the edge of the plate and 2" or more from any previous impacts. SAPI plates must be able to handle 3 such impacts, but I'm not sure whether they must also be able to qualify for NIJ level III -- undoubtedly many will, even if it weren't strictly required.

The criterion for a threat being "defeated" in NIJ testing is that the projectile doesn't penetrate and the backing material (a kind of clay) is not deformed more than 44mm (1.73"). For the last impact to a particular part of the armor (the 6th in level III testing or the first and only in level IV testing), it wouldn't matter if the armor promptly crumbled into dust, it'd have done its job.

My understanding is that the 7.62x51mm M993 AP round (12mm RHA at 200 meters) will fully penetrate many/most rifle plates, even those rated IV (which neither SAPI nor ESAPI plates are technically required to be AFAIK, even if many individual plates are) and their flexible vest backing and still be capable of causing lethal injury. What usually happens to the plate at this point, I have no idea. I've never seen a picture of that kind of thing happening.

The .50 BMG M33 ball round can penetrate almost twice as much armor steel as the M993 AP round at more than twice the range. I would be simply amazed if any rifle plate on the market would even be able to slow it down to shotgun slug speeds -- at which point it would still be able to crush a big-ass hole right through your torso no problem.

re: penetration and energy bleeding, anything that penetrates a vest is going to have enough kinetic energy left to punch through flesh. depending on the round, you might get lucky and slow it enough that it could bounce off of bone, but there's no telling how it will bounce--it might deflect off and exit the body without doing further damage, or it could pinball through the heart on its way through the lungs. if it gets through your vest, it's got about as much chance of killing you as if you hadn't worn a vest at all.